The present invention relates generally to optical print head media sensors used for detecting movement of media stock and, more particularly, to a media sensor system for a label printer mechanism, which media sensor system is configurable for detecting multiple types of label stock.
Label printing mechanisms commonly utilize a media stock in the form of a roll of a backing material with the label secured thereto, where the label can be easily peeled from the backing material after passing by a print head which is used to print information on the label. Of course, even with label printer mechanisms various types of label stock are commonly available for use in association with the printer mechanism. For example, a first type of media stock may commonly be used with a given printer mechanism in the United States while another type of label stock may be more commonly used or even required in foreign countries. Proper detection and feed of the different types of label or media stock utilizing a given printer mechanism often proves difficult.
Prior art printer mechanisms have used optical techniques for detecting label stock movement. However, to date no printer mechanism has provided a sensor arrangement which provides a selection capability according to the type of media stock to be used.
Accordingly, it would be advantageous to provide a printer mechanism with a media sensor system which permits a printer mechanism to be configured for use with various types of media stock.
In one aspect of the invention, a printer media sensor system includes a media stock guide having a first guide rail and a second guide rail spaced apart to allow media stock to pass therebetween. A light source is positioned on the first guide rail and passing to direct light toward the second guide rail. A first photo-detector is positioned on the first guide rail and positioned for detecting light emitted from the light source and reflected from media stock passing between the first and second guide rails. A second photo-detector is positioned on the second guide rail and positioned for detecting light emitted from the light source and passing through the media stock. Either photo-detector may be selected for use in monitoring movement of media stock enabling a printer mechanism including the media sensor system to be configured for use with various types of media stock.
In another aspect of the invention, a method of tracking media stock movement in a printer mechanism includes providing a light source for directing light toward media stock, providing a first photo-detector for detecting light reflected from media stock, and providing a second photo-detector for detecting light transmitted through media stock. An energization level of the light source is selectively controlled based upon a type of media stock being used in the printer mechanism. Similarly, it is preferred that movement of a media stock feed roller is controlled according to signals received from the first photo-detector when a first media stock type is used in the printer mechanism, and movement of the media stock feed roller is controlled according to signals received from the second photo-detector when a second media stock type is used in the printer mechanism.
In a further aspect of the present invention, a method of configuring a printer mechanism for use with one of a plurality of media stocks involves providing a light source for directing light toward media stock. A first photo-detector is provided for receiving light emitted from the light source and reflected from media stock. A second photo-detector is provided for receiving light emitted from the light source and transmitted through media stock. A type of media stock to be used in the printer mechanism is identified. An energization level of the light source is set based upon the identified media stock type, and one of the photo-detectors is selected for monitoring based upon the identified media stock type.